Mobile handsets, and services on mobile handsets (mobile handset also refers to embedded devices in e.g. PCs, laptops, vehicles etc.) have had a rapid evolution during the last decade. When 3GPP standardized GSM, and later 3G during the late 1980's and 1990's, circuit switched telephony and later Short Message Service (SMS) were pretty much the only services available. Since then, mobile handsets and networks have evolved to create powerful devices capable of running both local applications and browser based services, connected to a network providing a bandwidth high enough for TV and interactive multimedia. With the increasing bandwidth, and need to provide a feasible technical platform and transport technology for multimedia services, packet-switched networks, e.g., using Internet Protocol (IP) as the fundamental technology, are becoming the dominating platforms for mobile services. There are a number of reasons why this trend is being supported by most actors in the communications business. One reason is that third parties will start to develop applications for such systems, and just as in the case with Internet, this will likely be a key to the expected success of next generation technologies. Another reason is that IP provides a technology platform where it is cheaper to deploy functionality. This is to a large extent due to economy of scale, as technology also used by the IT industry is cheaper than traditional telecom technology.
Another aspect of mobile systems and devices which has experienced significant growth over the last 10 years or so is positioning or location-based services, e.g., services and associated techniques and mechanisms for determining a current location of a mobile phone. Initially introduced to, for example, support emergency (e.g., E911) services, positioning techniques and services will likely be used for other purposes in the future.
Fingerprinting positioning algorithms operate by creating a radio fingerprint for each point of a fine coordinate grid that covers the Radio Access Network (RAN). The fingerprint may, for example, include: (1) the cell IDs that are detected by the terminal (e.g., mobile phone) for each grid point, including Cell IDs detected which belong to other public land mobile networks (PLMNs) than the present PLMN to which that terminal is connected, (2) cell information broadcast by base stations, (3) quantized path loss or signal strength measurements, with respect to multiple Radio Base Stations (RBSs), performed by the terminal, in at least a subset of the grid points, (4) quantized Round Trip Time (RTT, in wideband code division multiple access (WCDMA)) or Timing Advance (TA, in GSM)), in each grid point, (5) quantized noise rise, representing the load of a CDMA system, in each grid point, (6) radio connection information, such as the radio access bearer (RAB), (7) quantized time. Using such information, whenever a position request arrives to the fingerprinting positioning function, a radio fingerprint is first measured, after which the corresponding grid point is looked up and reported. Naturally, the point to be reported should be unique, otherwise special procedures need to be applied.
The fingerprinted positions can be generated in several ways. For example, a first alternative would be to perform an extensive surveying operation that performs fingerprinting radio measurements repeatedly for all coordinate grid points of the RAN. The disadvantages of this approach includes: (1) the surveying required becomes substantial, even for small cellular networks, and (2) the radio fingerprints are, at least in some instants (e.g., those associated with signal strength and pathloss), sensitive to the orientation of the terminal, a fact that is particularly troublesome for handheld terminals. For fine grids, the accuracies of the fingerprinted positions therefore become more highly uncertain. This is unfortunately seldom reflected in the accuracy of the reported geographical shape.
Another approach, applied, e.g., in Adaptive Enhanced Cell IDentity positioning (AECID), is to replace the fine grid by high precision position measurements of opportunity, and to provide fingerprinting radio measurements for those points. This avoids the drawbacks of the first described fingerprinting technique, however it requires that algorithms for clustering of high precision position measurements of opportunity be defined and that algorithms for computation of geographical descriptions of the clusters be defined. More details regarding exemplary AECID techniques and mechanisms are provided below. Patent Applications authored by T. Wigren, PCT/SE2005/001485 entitled “Adaptive Enhanced Cell Identity Positioning”, and PCT/SE2006/000132, entitled “Path Loss Polygon Positioning”, the disclosures of which are incorporated herein by reference, fully describe these techniques.
Recently, some service providers, e.g., Google, have initiated an alternative to conventional cellular positioning methods. Their approach is based on standardised interfaces (e.g., Java Micro edition, Symbian, Linux and Windows for Mobile) for applications in the cell phone. Such interfaces make it possible to access cell data, neighbour cell lists and the results of basic measurement information that is available in the mobile phone or terminal for other purposes. This alternative is further based on means to retrieve a reference position, typically using GPS or Assisted GPS (A-GPS) data, given the availability of such features in a sufficient number of phones. Basically, when a GPS (or A-GPS) positioning is performed, the interface is exploited in order to report available position related information to a server, e.g., owned and operated by the service provider. The so obtained GPS positions, together with the associated information available via the software interface, allows the service provider to, for example, build up globally valid mappings of cell ID/Network ID tagged with globally valid and accurate positions by correlating these bits of information in their server. Furthermore, corresponding neighbour cell relations can be constructed.
However, the present techniques are limited to the information that is available in the terminal device, i.e., information that was collected by the terminal device at the request of the RAN, and also to information that was obtained in the past, i.e., information that may be outdated.
Thus, for the positioning techniques, systems and methods which use the service provider controlled interfaces within the terminal device, as described above, it would be beneficial to obtain, and use, additional positioning related information.